The pores in the filtering surface of dust containers used in vacuum cleaners become clogged after a certain period of operation, so that even if the dust container is only partially filled the pressure drop over the container wall has increased so much that an indicating device, which usually senses this pressure drop, gives a false indication that the container is filled, and should be exchanged. Of course, this situation is undesirable and, moreover, it is not economical.
Different types of filter shaking devices are known, which in most cases are mechanical and have a principal purpose of loosening the dust from the filter surface of the dust container, and in this way, results in the continued use of the dust container and the increase of filling capacity thereof. Often the contents of the dust container have a fluffy structure, which results in that the desired effect cannot be obtained by means of filter shaking only.
The present invention relates to a compressing device for a dust container, i.e. intended for vacuum cleaners, comprising a chamber with an inlet for dust laden air, an outlet for cleaned air and a motor fan unit for transporting air from the working implement through a suction hose and the dust container disposed in the chamber.
An object of the present invention is to eliminate the above-mentioned drawback and to construct a simple device for increasing the filling degree of the dust container. For this purpose the invention is mainly characterized in that the dust container, by changing the pressure conditions between the inside and outside, respectively, of the dust container, the latter is compressible so that its inner volume during a certain time interval becomes smaller than the original volume thereof.